Pulse modulation method
Technical field
The present invention relates to a kind of the code of being made up of a plurality of Bit datas be carried out pulse modulated pulse modulation method, relate in particular to the pulse modulation method that in infrared communications sets such as IR module, Long-distance Control transceiver, uses.
Background technology
In the past, in infrared remote transmitter, used impulse phase modulation (PPM) method with the action of infrared ray control home appliance etc. always.In the impulse phase modulator approach, with the data code of controlling the control data coding of controlled device and getting, PPM is modulated into and has set different pulses according to the value of its Bit data and rest the code modulated signal of interval T r, in order further to prevent interference, the misoperation with other equipment, with this PPM modulation signal the carrier modulation ripple of 38kHz has been carried out secondary modulation and the infrared ray modulated signals be sent to controlled device.
The impulse phase modulator approach that should generally use is at present rested interval T r for the data of per 1 bit with pulse and is represented its data, has therefore that TD during the transmission that is used to send whole code is elongated, the problem of transmission speed slows.Therefore, the applicant has invented following pulse modulation method: rest interval T r dividing code according to the unit of being made up of 2 Bit datas and set different pulses accordingly according to per 2 Bit datas of each unit, simultaneously TD during the transmission of modulated whole code modulated signal is compared with the situation that all Bit datas are overturn, when TD was shortened during sending after upset, the upset of the code modulated signal additional representation upset that the Bit data by upset is generated indicated and sends (with reference to patent documentation 1).
Patent documentation 1: No. 3153084 communique of patent (Instructions Page 3 project 0025 is to the 4th page of project 0045, Fig. 1 to Fig. 3)
Below, use Fig. 4 and Fig. 5 that this pulse modulation method is described.Fig. 4 (a) indicates to carry out the bit formation of pulse modulated code.As shown in the figure,, be divided into 8 unit, carry out pulse modulation according to each unit according to continuous per 2 Bit datas with ID code and data code totally 16 Bit datas.That is, produce the pulse signal of pulse duration t according to each unit, 2 Bit datas that make each unit afterwards are as data unit, set 4 kinds of pulses accordingly with the value of 2 Bit datas and rest interval T r, as 2 bit PPM modulation signals shown in Fig. 4 (b).And then 2 bit PPM modulation signals are in order to prevent interference, the misoperation with other equipment, shown in Fig. 4 (c), the carrier modulation ripple of 38kHz are sent to controlled device as the secondary modulation signal by infrared ray.
In this conventional example, shown in the normal mode of Fig. 5, behind the pulse signal that produces pulse duration t, when 2 Bit datas are (0,0), pulse are rested interval T r be set at identical distance with pulse duration t, when 2 Bit datas are (0,1), pulse are rested interval T r be set at 2t at interval, at 2 Bit datas is (1,0) time, pulse being rested interval T r be set at 3t at interval, is (1 at 2 Bit datas, 1) time, pulse is rested interval T r be set at 4t at interval.
Change between 40t when so the 16t of TD when all 2 Bit datas are (0,0) is (1,1) to all 2 Bit datas during the transmission of the code modulated signal of modulation.Therefore that is, TD changes according to the value of 16 Bit datas of code during the transmission, distributes short pulse to rest 2 Bit datas of interval T r if comprise more, TD shortens during then sending, otherwise, distribute long pulse to rest 2 Bit datas of interval T r if comprise more, TD is elongated during then sending.
TD is 7Nt according to the threshold X that the value of Bit data reverses during the transmission that is generated by 4N (N is a positive integer) Bit data.The pulse duration t that is comprised among the pulse spacing Tu of each unit of TD during the transmission equates in each unit of being made up of 2 Bit datas, therefore rest the summation of interval T r in the pulse of code modulated signal and be at least [5N+1] when t is above, 4 Bit datas are overturn shorten TD during the transmission, shown in the inverted pattern of Fig. 4 (d), make the value upset of all Bit datas, rest interval T r with the pulse of setting accordingly with the value of this upset and generate upset 2 bit PPM modulation signal code modulated signals (Fig. 4 (e)).
Then,, be included in the 2 bit PPM modulation signals, can transmit with TD during the transmission of having shortened code integral body thus with (0,1) indicator sign with carrying out the state of ovennodulation after Bit data is overturn.
The code modulated signal that uses in general infrared remote transmitters such as household appliances (2 bit PPM modulation signal) is sent to controlled device by the secondary modulation signal that the carrier wave of 38kHz is modulated.In the controlled device side, to after being included in infrared light in the secondary modulation signal that is subjected to light and carrying out opto-electronic conversion, in amplifying circuit, amplify, shown in Fig. 6 (b), compare amplifying the threshold value Vref of output, be demodulated to the code modulated signal shown in this figure (c) with regulation.
By the code modulated signal of demodulation, because the characteristic of amplifying circuit, rising and decline in pulse can postpone T1, T2 respectively, and these risings and the influence that descends because of the frequency characteristic of light-emitting component, photo detector, modulation-demodulation circuit, transmission path etc. change, and are not certain therefore.Therefore, by the code modulated signal of demodulation, further the interpulse rise interval of code modulated signal is set at the pulse spacing Tu of the pulse unit of forming by 2 Bit datas, from pulse spacing Tu demodulation 2 Bit datas.
Summary of the invention
Yet, even from the PPM modulator approach of pulse spacing Tu demodulation 2 Bit datas of pulse unit, sometimes also can be and the demodulation mistake takes place because of the variation of the rising of the pulse that causes by transmission environment or decline.For example, when the distance between infrared remote transmitter and controlled device is near, amplifying output voltage rises along with the increase of light income, shown in Fig. 6 (c1), the rise time T3 of pulse is more Zao than T1, on the contrary, owing to become the following time delay of threshold value Vref, so fall time, T4 significantly postponed than T2.
Pulse duration Pw ' this moment (Fig. 6 (c1)) is main to be increased because of the delay of rise time T4, overlapping with the rising of next pulse when therefore the pulse of the code modulated signal before its recruitment surpasses modulation rests interval T r, becomes the demodulation mistake.
The pulse duration t of the recruitment of pulse duration Pw ' code modulated signal of general 12 times of left and right sides length that can not surpass the cycle tc that is set at carrier wave in infrared modulated signals, therefore in above-mentioned pulse modulation method, the shortest pulse of code modulated signal is rested interval T r to be set at pulse duration t and to equate, even the delay of rise time T4 is arranged, also can demodulation.Yet, set accordingly with the proportional 4 kinds of pulses of pulse duration t with 4 kinds of combinations of 2 Bit datas and to rest interval T r, so 5 times the pulse spacing Tu of maximum pulse t is assigned to 2 Bit datas, can't shorten sending interval T D fully.
Therefore, in patent documentation 1, also disclose for resting each of interval T r and multiply by identical Compression Constant k below 1 with the proportional 4 kinds of pulses of pulse duration t, shorten the method for TD during the transmission of code modulated signal integral body, but rest in the pulse unit of interval T r setting the shortest pulse, because pulse rests interval T r and becomes below the pulse duration t of original signal, therefore there is the possibility that above-mentioned demodulation mistake takes place, also exists in simultaneously to be demodulated to mistakenly under the environment that the light income of infrared modulated signals lowers and set different pulses and rest the problem of 2 Bit datas of interval T r.
Promptly, between infrared remote control transmitter and controlled device during distance, because the light income of controlled device reduces, therefore it is slow to amplify rise of output voltage, shown in Fig. 6 (c2), the rise time T5 of pulse is more late than T1, and is opposite, owing to become immediately below the threshold value Vref after be interrupted halfway by light, so fall time, T6 significantly shifted to an earlier date than T2.Under such transmission environment, the rise time T5 instability of pulse, the pulse spacing hole of the pulse train of demodulation can produce about 1/2 the error of pulse duration t before the maximum modulation.Therefore, multiply by Compression Constant k below 1 on 4 kinds of pulses setting accordingly with 2 Bit datas rest interval T r shortens under its situation at interval and also has the possibility that the demodulation mistake takes place because of transmission environment.
The present invention considers that so existing problem forms, its purpose is to provide a kind of pulse modulation method, this pulse modulation method shortens TD during the transmission of the code of being made up of a plurality of Bit datas, even also demodulation Bit data reliably under the situation of shaking because of transmission environment in pulse.
In order to achieve the above object, claim 1 provides a kind of pulse modulation method, this pulse modulation method will be divided according to the unit that is made of 2 Bit datas by the code that 4N (N is a positive integer) Bit data is formed, after each unit being produced the pulse signal of fixed pulse width tw, be created on the pulse of setting accordingly with each value of 2 Bit datas of this unit rest interval T r during pulse signal is rested code modulated signal, and make the code modulated signal of each unit continuous, it is characterized in that, with more than 1/2 of fixed pulse width tw, any adjustment time width less than 1 is made as Δ t, and what 4 values of 2 Bit datas were set in time interval of approximating fixed pulse width tw accordingly fixedly adds 0 between the down-time period on the tm, Δ t, 2 Δ t, any one time width among the 3 Δ t and 4 kinds of pulses rest interval T r, when the summation TD of the code modulated signal that generates from 4N (N is a positive integer) Bit data is at least interval [(2tw+2tm+3 Δ t) N+ Δ t] more than, with the pulse of each unit rest interval T r be replaced into and make each unit 2 Bit datas the value upset and must the pulse set accordingly of 2 Bit datas rest interval T r; Use pulse after the displacement to rest interval T r, from all unit generating code modulation signals; The upset marking signal of additional representation upset information on continuous code modulated signal.
In the invention of claim 1, to divide according to the unit that constitutes by 2 Bit datas by the code that a plurality of Bit datas are formed, 2 Bit datas are carried out the impulse phase modulation as data unit, the demodulation of code modulated signal is from the pulse spacing Tu of the interval detecting unit unit between the rising edge of pulse train, carries out demodulation according to 2 Bit datas.Owing to form pulse, therefore can shorten TD during the transmission of code modulated signal of expression code according to 2 Bit datas.
4 kinds of pulses setting accordingly with each value of 2 Bit datas rest interval T r, comprise at least about the time interval that equals fixed pulse width tw fixedly rest interval tm, so the demodulation mistake can not take place because of transmission environment increases also in pulse duration.In addition, the time difference Δ t that 4 kinds of pulses rest between the interval T r is more than 1/2 of fixed pulse width tw because of rising time interval the latest of transmission environment pulse, even therefore the demodulation mistake can not take place in the rise time instability of pulse yet, and, owing to be set at, therefore can shorten TD during the whole transmission less than fixed pulse width tw.
Be at least [(2tw+2tm+3 Δ t) N+ Δ t] when above at the summation TD of the code modulated signal that generates from 4N (N is a positive integer) Bit data, the pulse that the spy of use and upset sets accordingly than the value of data rests interval T r generating code modulation signal, therefore can further shorten TD during the whole transmission.Upset information can be differentiated with the upset marking signal that is attached on the code modulated signal, under the situation that makes Bit data upset and modulation, makes the Bit data upset in the demodulation of demodulator circuit side, can demodulation 4N Bit data.
The pulse modulation method of claim 2, it is characterized in that, with upset information set accordingly fixedly rest tm at interval and fixedly rest add Δ t on the tm at interval and must 2 kinds of pulses of time rest interval T r, behind the pulse signal that produces fixed pulse width tw, the pulse of setting accordingly with upset information rest interval T r during pulse signal rested and generate the upset marking signal.
Upset information is to transmit by the upset marking signal with the same form of code modulated signal, and is short during therefore sending, and the demodulation mistake can not take place.
Invention according to claim 1, the shortest pulse that comprises in the code modulated signal of each unit of expression 2 Bit datas rests interval T r and approximates fixed pulse width tw, even therefore the timing variation of rising, descending because of transmission environment, pulse duration increase, also be can demodulation code modulated signal, can make the shortest pulse and rest at interval.
4 kinds of code modulated signals of 2 Bit datas, at least the phase difference that has the Δ t that also can discern when rising because of the transmission environment pulse changes, therefore can carry out demodulation reliably, and can set 4 kinds of pulses from the combination in the shortest time interval and rest interval T r.Therefore, but rest the combination of interval T r according to the shortest pulse of fixed pulse width tw and demodulation and can shorten to TD during the transmission of code integral body the shortest.
Therefore 4 kinds of each code modulated signals of 2 Bit datas are to use every the arithmetic series of Δ t to represent, make the Bit data upset according to its mean value, can obtain shortening the threshold value of TD during the transmission easily.
According to the invention of claim 2, use the modulator approach identical to modulate with code, therefore use the modulation-demodulation circuit identical to transmit upset information with code.Use short 2 kinds that the 4 kind pulses corresponding with 2 Bit datas rest among the interval T r to generate the upset marking signal, TF integral body during therefore can shortening the frame that comprises upset information and sending.
Description of drawings
Fig. 1 is by the form of the code of the pulse modulation method modulation of one embodiment of the present invention and the oscillogram of code modulated signal.
Fig. 2 is the normal mode of pulse modulation method and the modulation format figure of inverted pattern.
Fig. 3 is a key diagram of obtaining the threshold X of 4 Bit datas.
Fig. 4 is the oscillogram with the code modulated signal of the form of the code of existing pulse modulation method modulation.
Fig. 5 is the normal mode of existing pulse modulation method and the modulation format figure of inverted pattern.
Fig. 6 is the pulse train of emission pusher side and at the comparison diagram of the pulse train of receiver side demodulation; (a) be the oscillogram that sends pulse; (b) be expression with the comparator of receiver side relatively amplifying signal and the oscillogram of the relation between the threshold value; (c) be the oscillogram of the output of expression comparator; (c1) be the oscillogram that is illustrated in the output of the level of the modulation signal that receiver side the receives comparator when high; (c2) be the oscillogram that is illustrated in the output of the level of the modulation signal that receiver side the receives comparator when low.
Symbol description
Tw: fixed pulse width;
Tm: fixedly between the down-time period
Δ t: adjust time width
Tr: pulse rests at interval
Tu: during the transmission of every unit
TD: during the transmission of code modulated signal.
Embodiment
Below, referring to figs. 1 through Fig. 3 the pulse modulation method of one embodiment of the present invention is described.Fig. 1 (a) expression constitutes by the bit that this execution mode carries out pulse modulated code.In order to compare,, make identical respectively Bit data by the code that ID code that is made of 8 Bit datas respectively and data code are formed with existing P PM modulator approach shown in Figure 4.The ID code is that the attribute according to controlled device determines, is used to prevent and the misoperation of other equipment that data code is encoded the control data of control controlled device and obtained.
16 Bit datas of ID code and data code are divided into 8 unit by 2 continuous Bit datas, and each unit is carried out the impulse phase modulation.Promptly, each unit is produced the pulse signal of fixed pulse width tw, afterwards with 2 Bit datas of each unit as data unit, pulse rests some among the interval T r in shown in the value normal mode that set accordingly, Fig. 2 of additional and 2 Bit datas 4, make the modulation signal of all unit of generation continuous, make the code modulated signal shown in Fig. 1 (b).
Use Fig. 2 that it is illustrated in greater detail,, irrespectively generate the pulse signal of the fixed pulse width tw of same widths with the value of 2 Bit datas then in each unit.Fixed pulse width tw need be set at the length more than at least 10 times of the cycle tc of carrier wave, so that the envelope of carrier wave surpasses the threshold value Vref shown in Fig. 6 (b), demodulation reliably, at this, because the frequency of the carrier wave of general infrared remote transmitter is 38kHz, its cycle tc is about 26.3 μ sec, and therefore, 12 times the length that pulse duration tw is made as the cycle tc of carrier wave is 316 μ sec.Below, be each time width of unit representation code modulated signal with the cycle tc of carrier wave, the time width of fixed pulse width tw is represented with 12tc.
And 4 kinds of pulses that 4 values of 2 Bit datas are set accordingly rest interval T r be the time interval that approximates fixed pulse width tw fixedly append 0 between the down-time period on the tm, some among Δ t, 2 Δ t, the 3 Δ t and generating.Therefore, the code modulated signal of each unit has maximum recruitment that the pulse duration than anticipation increases because of transmission environment between the long pulse down-time period, and the demodulation mistake that the pulse overlap because of front and back causes can not take place.
Δ t is more than 1/2 of fixed pulse width tw, the time width of adjustment arbitrarily less than 1, is made as 1/2 the 6tc (158 μ sec) of fixed pulse width tw here.Between the pulse spacing of each unit of forming by 2 Bit datas Tu, can guarantee the difference more than 1/2 of fixed pulse width tw at least thus, even the light income of controlled device side reduces, the lifting position of pulse is the limit change with 1/4 of fixed pulse width tw respectively, can not be demodulated into other Bit datas mistakenly separating timing with pulse spacing Tu yet.
Rest interval T r with 4 kinds of pulses that each value of 2 Bit datas is set accordingly and can be set at identical pulse and rest interval T r, also can set to make up arbitrarily.But, at this, shown in the normal mode of Fig. 2, being set at when 2 Bit datas are (0,0) and fixedly resting at interval tm, is (0 at 2 Bit datas, 1) time, be set at fixedly rest append Δ t on the tm at interval and the interval, when 2 Bit datas are (1,0), be set at fixedly rest append 2 Δ t on the tm at interval and the interval, when 2 Bit datas are (1,1), be set at fixedly rest append 3 Δ t on the tm at interval and the interval.Therefore, the 45tc that the pulse spacing Tu of the maximum of a unit just gets fixedly appending 3 Δ t between the down-time period on the tm, the maximum impulse interval T u of the existing method when pulse duration is made as identical 12tc is that the situation of 60tc is compared, and transmitting time significantly shortens.
As hereinafter described, when the summation TD of the code modulated signal that the modulation signal of all unit is continuous has surpassed threshold X, shown in the inverted pattern of Fig. 2, set pulse for 2 Bit datas of each unit and rest interval T r.Promptly, set accordingly with the value upset of 2 Bit datas of each unit and value accordingly, the pulse set in normal mode rests interval T r, the pulse that use is set in inverted pattern rests interval T r, with the method identical with normal mode, from all unit generating code modulation signals.
About having generated code modulated signal with which pattern in normal mode and the inverted pattern, as shown in Figure 1, be used in upset sign (upset information) expression of forming by 2 Bit datas of appending before the ID code, use the modulator approach identical that the upset marking signal is carried out the impulse phase modulation with code modulated signal.Here, use with 2 Bit datas of each unit same form and represent normal mode and inverted pattern, that is, normal mode is expressed as (0,0), inverted pattern is expressed as (0,1), set the pulse corresponding with normal mode and rest interval T r with 2 Bit datas.Promptly, the upset sign of expression normal mode be modulated to make fixedly rest tm at interval in succession fixed pulse width tw and upset tags modulate signal, the upset sign of expression inverted pattern be modulated to make Δ t and fixedly rest tm addition at interval and get pulse rest interval T r in succession at fixed pulse width tw and the upset tags modulate signal that gets.
Like this each unit to 2 Bit datas carry out impulse phase modulation and code modulated signal before append stem signal and upset tags modulate signal, in addition, append tail signal thereafter, generate the 2 bit PPM modulation signals of Fig. 1 (b) or Fig. 1 (d).
For prevent and other equipment between interference, misoperation, these 2 bits PPM modulation signal further make the carrier modulation ripple of 38kHz modulated and Fig. 1 (c) shown in the secondary modulation signal, be sent to controlled device by ultrared mode.
In normal mode, will by the code that 16 Bit datas are formed modulate and the transmission of code modulated signal during TD, be (0 from all 2 Bit datas, change between the 360tc (9.47msec) when the 216tc in the time of 0) (5.68msec) is (1,1) to all 2 Bit datas, be (0 if comprise 2 Bit datas in unit 8 more, 0) or (0,1) unit, TD shortens during the then above-mentioned transmission, otherwise, if comprise (1 more, 0) or the unit of (0,1), then elongated.
That is, when TD has surpassed threshold X during the transmission of the code modulated signal of 16 Bit datas, if make 16 Bit datas all data upsets, carry out the impulse phase modulation according to the inverted pattern of Fig. 2, TF during then can shortening during the transmission TD or frame and sending.Below, with reference to Fig. 3 this threshold X is described.
Fig. 3 carries out TD during the transmission of the combination of 2 Bit datas of impulse phase when modulation, each unit and the code modulated signal that determines according to this combination to 4 Bit datas with normal mode.As shown in the figure, the pulse spacing Tu of each unit be fixed pulse width tw and pulse rest interval T r and, if will be in each unit common fixed pulse width tw and fixedly rest tm at interval be made as ta, then the pulse spacing Tu of each unit is from ta some to the ta+3 Δ t.
4 Bit datas are made up of the combination of upper 2 Bit datas and the next 2 Bit datas, during the transmission of code modulated signal TD be each unit pulse spacing Tu's and, therefore TD is 2ta when (0000) during sending, and is 2ta+6 Δ t when (1111).The combination of representing with the lower-left oblique line is the combination that TD shortens during the transmission when upset 4 Bit datas in the drawings, even the combination of representing with the bottom right oblique line is 4 Bit datas that overturn, sends the combination that interval T D also can not change.That is, the threshold X during 4 Bit datas is 2ta+3 Δ t.
Generally, the pulse spacing Tu of a unit is from ta some to the ta+3 Δ t, therefore its mean value is ta+1.5 Δ t, because 4N (N is a positive integer) Bit data is split into 2N unit, therefore the 4N Bit data is carried out that the desired value of TD is (ta+1.5 Δ t) * 2N=(2ta+3 Δ t) N during the transmission after impulse phase is modulated.That is, this desired value becomes the value of the threshold X of 4N Bit data.Therefore, when TD surpasses (2ta+3 Δ t) N during the transmission of the code modulated signal of 4N Bit data, the pulse that use makes the value upset of 2 Bit datas, set at the value of this upset rests interval T r generating code modulation signal, and this can shorten TD during the whole transmission.
In the present embodiment, ta is fixed pulse width tw and fixedly rests at interval tm's and be 27tc, and Δ t is 6tc, so the threshold X of 4 Bit datas is 72Ntc, is 288tc in 16 Bit datas.In code shown in Figure 1, be 306tc with TD during the transmission of the code modulated signal of normal mode modulation, surpass threshold value 288tc, therefore will overturn indicates and is made as (0,1), generates the code modulated signal of each unit with inverted pattern.For example, shown in Fig. 1 (d), for (1,0) 2 Bit datas, be set at (0,1) pulse of She Dinging rest interval T r promptly fixedly rest add Δ t on the tm at interval and interval 21tc, be created on the fixed pulse width tw of 12tc the pulse of 21tc in succession rest interval T r and the code modulated signal of pulse spacing Tu of 33tc.
With inverted pattern when 16 Bit datas be made up of ID code shown in Fig. 1 (a) and data code generate code modulated signal shown in Fig. 1 (d), TD became 270tc during it sent, and shortened during TD306tc compares transmission during the transmission in the normal mode.
In addition, in the present embodiment, after the sign that will overturn carries out pulse modulation with normal mode,, in fact do not make the value upset of Bit data, handle easily, directly carry out pulse modulation with inverted pattern shown in Figure 2 in order to make about 16 Bit datas.
Appending upset sign and carrying out the demodulation of pulse modulation method of the present embodiment of impulse phase modulation, the pulse spacing Tu of upset tags modulate signal is relatively also decoded with the normal mode of Fig. 2, if (0,0), then use each Bit data of normal mode demodulation of Fig. 2 from the code modulated of demodulation, if (0,1) then carries out demodulation with inverted pattern.
In the above-described embodiment, when TD equals threshold value during the transmission of 4N Bit data in normal mode, can carry out pulse modulation with any one pattern in normal mode, the inverted pattern.
In addition, in Fig. 2, also normal mode can be made inverted pattern, inverted pattern is made normal mode come that each Bit data is set pulse and rest interval T r, and, 4 values of 2 Bit datas and 4 kinds of pulses rest combination at interval and are not limited to present embodiment, only otherwise repeat, can be different arbitrarily combinations.
Utilizability on the industry
The present invention is applicable to use code has been carried out the communication that the modulation signal of impulse phase modulation sends Device.